C-clamp with slidable plunger



Dec. 9, 1958 D. SAGERTY 2,853,477

C-CLAMP WITH SLIDABLE PLUNGER Filed March 7, 1956 INVENTOR. LEONARD D. AGE/PT) A TTORNEVS United States 1 Patent Office 2,863,477. Patented Dec. 9, 1958 C-CLAMP WITH SLIDABLE PLUNGER Leonard D. Sagerty, Campbell, Calif. Application March 7, 1956, Serial No. 570,200

2 Claims. ((31. 144-305 The present invention relates to clamps and pertains more particularly to a C-clamp having a slidably acting, lever operated plunger as the movable jaw thereof.

In the past, numerous attempts have been made to improve on the conventional C-clamp with its generally C-shape rigid frame, and a presser screw threadedly mounted in one extremity of the frame and directed toward the other extremity thereof.

Some of these prior attempts to improve upon the C-clamp have provided a slidably mounted plunger to replace the conventional presser screw, with various means for securing the plunger in compressive relation with a work piece mounted between the inner end of the plunger and the opposite extremity of the frame. However, in some such prior attempts the plunger displayed a tendency to jam and hang up at times, and the axial force applied to the plunger frequently was not of sufi'icient magnitude to properly grip a work piece.

The present invention contemplates the provision of an improved and simplified cam-section C-clamp.

The invention also provides a quick-acting clamp having a C-shapecl rigid frame with a mounted in one extremity.thereof, the plunger being operatively associated with a cam-actuated lever which, in its outward limit of its movement, insures alignment of the plunger with holes in the frame and in the camactuated lever in which it is mounted. Upon an operative stroke of an actuating lever, the cam-actuated lever is swung inwardly to first grip the plunger, and then to advance the latter positively toward a work piece gripped between the plunger and the opposite extremity of the frame.

A further object of the invention is to provide a clamp having a slidable, work piece engaging plunger, with improved, lever mounted, cam actuated operating means.

These and other objects and advantages of the inven tion will be apparent from the following description and the accompanying drawings, wherein Fig. 1 is a side elevation of a C-clamp embodying the present invention, portions thereof being shown in section, and a Work piece being indicated in broken lines gripped between the plunger and the opposite extremity of the frame.

Fig. 2 is a fragmentary view similar to the lower portion of the clamp illustrated in Fig. l, but with the operating lever shown in solid lines partly advanced toward a clamping condition, and in broken lines in full'clamping condition.

Fig. 3 is a fragmentary perspective view showing the lower portion of the clamp illustrated in Figs. 1 and 2 with the parts in fully clamped condition, portions being broken away.

Briefly, a clamp A embodying the invention is shown in Figs. 1, 2 and 3. The clamp A comprises a rigid, C-shaped metal frame having a work gripping plunger 11 slidably mounted in a hole 12 provided in one extremity of the frame 10 and axially directed toward a plunger slidably jaw pad 13 on the other extremity of the frame. A cam actuated lever 14 is pivotally mounted on. the frame 10 and has a conical hole 15 therethrough in which is mounted a correspondingly shaped conical split collar 17 which is fitted slidably onto the plunger 11. The split collar 17 is urged outwardly into the hole 15 by a coil spring 18 which loosely encircles the plunger 11.

The carn actuated lever 14 is moved from its plungerreleasing position in its outward limit of movement of Fig. 1, to its inwardly swung, plunger gripping and advancing position shown in broken lines in Fig. 2 by an operating lever 20 which is pivotally mounted between the lower ends of a pair of arms 21 which are provided one on each side of the frame 10.

Referring now to the drawings in greater detail, the C-shaped frame 10 preferably is a steel forging of generally T-shapcd cros sectional shape as best shown in Fig. 3. The pad 13, comprising the fixed jaw of the device, may be formed integrally in one end of the frame 10 in a manner which is conventional for C-clamps.

The web 22 forming the stem portion of the generally T-shaped frame 10 is relieved at 23 to receive the camactuated lever 14, which has a notch 24 in one end thereof to straddle the frame web 22, and is pivotally mounted thereon by a pivot pin 25. The cam actuated lever is? is guided against transverse displacement by the arms it, which may be formed integrally with the frame 1% and extend downwardly therefrom as shown in Figs. 1-3 in generally parallel relation.

A limit stop pin 27 for the cam actuated lever 14 is mounted medially of the arms 21 to extend transversely therebetwcen. This pin rides in a slot 23 provided therefor in the lever 1d. The slot 23 is of a length to allow free inward movement of the lever 14, but to bring the inner end of the slot into engagement with the stop pin 27 at a predetermined outward limit of movement of t he cam actuated lever 14, at which point the conical hole 15 in thelever 14 will be coaxial with the plunger hoie 12 in the frame 10.

The coil spring 18 is quite strong, but is of a length to be fully extended when the lever 14 is in its outermost or released position shown in Fig. 1 so as to free the split collar 17 in its conical seat 1'5.

The operating lever 20 is pivotally mounted on a pin 29, which extends transversely across the lower ends of the arms 21. The operating lever 20 has a cam nose 3% formed thereon which preferably rides in an arcuate depression 31 in the lever 14. The depression is not concentric with the pivot pin 29 in any position of the lever 20, but is so formed that as the operating lever 20 is swung from its releasing position shown in Fig. 1 ,toward its clamping position shown in Fig. 2, the cam 39 will gradually depress the cam actuated lever 14 toward its full clamping condition shown in Fig. 2.

A friction reducing cam roller 32 preferably is mounted with itsperiphery exposed slightly beyond the cam 36 so that the roller will act as a cam nose on the operating lever as it is swung from its releasing to its clamping position and reversely.

The cam roller 32 is so mounted on the cam 30 that when the operating lever 20 is in its fully actuated or clamping position shown in broken lines in Fig. 2, the roller will be slightly beyond a dead center position. Thus, the outward pressure on the plunger 11 in its clamping condition tends to swing the operating lever 20 even more tightly against the frame in locked condition, and prevents accidental release of the clamp.

In operating the clamp A, the operating lever 20 is swung outwardly to its releasing position shown in Fig. 1, in which position the pressure of the coil spring 18 is relieved from the inner end of the split collar 17, and the plunger 11 is axially aligned with the hole 12 in the frame and also with the conical hole in the cam actuated lever 14 and the split collar 17 seated therein. In this condition of the parts, the plunger 11 may be freely moved axially toward or away from a work piece B by means of a knob 34 which is providedon the outer end of the plunger 11.

The clamp A is fitted over the work piece B, indicated in broken lines in Fig. 1, and theplunger 11 is slidably moved to grip the work piece loosely, between the fixed jaw pad 13 and the inner end of the plunger 11', which, as illustrated, is also provided witha pad '35.

With a clamp A of a size of the order of four or five inches maximum opening between the jaw pads 13 and 35, the clamp may be conveniently operated by a workman using only one hand, which is an important advantage of the present clamp over a conventional screw type C-clarnp.

With the work piece B loosely gripped between the jaw pads 13 and 35, the operating lever -may be swung from its releasing position shown in Fig. 1 to its clamping position shown in broken lines in Fig. 2. As the operating lever 29 is swung in a counter-clockwise direction from its position of Fig. 1, the cam nose or roller 32 moves into camming engagement with the arcuate depression 31 in the outer face of the camactuated lever 14. This swings the cam actuated lever 14 so that the conical hole 15 therein is tilted from its position of axial alignment with the plunger 11, thereby tilting the split collar seated in the hole 15 relative to the plunger. This causes the sleeve to bind on and thus to grip the plunger, carrying it axially inwardly with the cam actuated lever 14. As the split collar 17 is carried inwardly with the plunger, the coil spring 18 I is compressed, tending to urge the collar 17 more tightly into its conical scat, which action tends to wedge the split collar 1? still more tightly about the plunger and thus to grip it even more firmly.

The plunger 11 thus is very forcibly gripped by the split collar 17 and is further very forcibly advanced by cam roller 32 on the operating lever 20 into gripping relation with the work piece B, thereby firmly holding the work piece in tightly gripped relation between the fixed jaw pad 13 and the plunger pad 35. Returning the operating lever 20 clockwise from its fully actuated, broken line position in Fig. 2, through the solid line position of Fig. 2 to its fully released position of Fig. l, restores the conical hole 15 with the split collar 17 therein into axial alignment with the plunger 2! and simultaneously releases the pressure of the coil spring 18 from the inner face of the split collar 17. This frees the plunger 11 for easy axial sliding movement in the frame hole 12.

The device comprises a strong and simple clamp, which may be easily operated with one hand and which insures release of the plunger when the operating lever is moved to its releasing position.

While I have illustrated and describeda preferred embodiment of the present inventionit will be understood however, that various changes and modifications may be made in the details thereof without departing from the scope of the invention as set forth in the appended claims.

Having thus described the invention, what I claim as new and desire to protect by Letters Patent is defined in the following claims.

1. A quick-acting clamp comprising a C-shaped frame,

a plunger slidably mounted in a hole in one frame extremity for axial slidable movement toward the other frame extremity, a clamping lever pivotally mounted exteriorly of the frame extremity having the plunger mounted thereon, said lever having a tapered hole therein with its larger end-toward the frame, stop means limiting outward pivotal movement of the clamping lever to a position axially aligning the tapered hole with the plunger, an externally tapered split collar fittedinto the tapered hole and mounted co-axially, and normally slidably, on the plunger, a compression spring mounted between the frame and the split collar to urge the clamping lever outwardly, said spring being free from pressure on the collar in the outward limit of movement of the clamping lever, and cam means mounted for operative engagement with the clamping lever for; swingingthe;

clamping lever inwardly toward the frame thereby compressing the spring against the collar and forcing the collar, into its tapered hole for binding engagement with the plunger, pivotal movement of the clamping leverv urging the collar out of axial alignment with the plunger to further bind the collar onto the plunger for forcible inward axial movement of the plunger during an inward swinging movement of the clamping lever.

2. A quick-acting clamp comprising a C-shaped frame, a plunger slidably mounted on one frame extremity for movement towardthe other frame extremity, a clamping lever pivotally mounted exteriorly on the frame adjacent said plunger and having a tapered hole therein, with its larger end toward the frame, stop means limiting outward pivotal movement of the clamping lever to a position axially aligning the tapered hole with the plunger, wedge means externally taperedon a taper corresponding to that of the tapered hole and fitted into the tapered hole and normally slidable along the plunger, a compression spring mounted between the frame and the wedge means and free from pressure on the wedge means in the outward limit of movement of the clamping lever, whereby an initial operative movement of the clamping lever toward the frame compresses the spring against the wedge means, thereby forcing the latter into binding engagement with the plunger, and further pivotal movement of the clamping lever tilts the tapered hole therein away from axial alignment with the plunger to bind the wedge meansv more firmly to the clamping lever, and.

urges the plunger axially toward said other frame extremity.

References Cited in the tile of this patent UNITED STATES PATENTS 

